1. Field of the Invention
The present invention relates to a method for manufacturing a semiconductor device.
2. Description of the Related Art
In recent years, a thin-shaped display device typified by a liquid crystal display device or an electro luminescent display device (also referred to as an EL display device) has become popular; accordingly, a thin film transistor technology, which is one of its main technologies, has been actively researched and developed. By improving performance of a thin film transistor and increasing productivity thereof, a thin-shaped display device having excellent display performance can be provided at low cost. Accordingly, such a thin-shaped display device can maintain advantage in the market of thin-shaped display devices.
As an example of a method for improving performance of a thin film transistor, a method in which crystallinity of a semiconductor film is improved is given. In Patent Document 1, for example, a technique in which a nickel element is added to silicon to promote crystallization, thereby improving characteristics of a thin film transistor is disclosed.
Further, in Patent Document 2, a technique in which crystallization of a semiconductor film is promoted by heat treatment at multiple steps is disclosed.